The Story Behind Saturn’s Rings

New research may explain how the planet’s famous rings formed

Saturn’s rings are made of countless particles of ice and rock. (Photo Researchers / Getty Images)

Saturn’s rings have fascinated observers here on Earth since the Italian astronomer Galileo first spotted them in 1610. Where did these rings come from? What are they made of? Recent research may provide new clues as to how the planet’s curious circles were created.

The United States and 16 European countries sent a robotic spacecraft named Cassini-Huygens to orbit (circle around) Saturn in 1997. Over the years, the spacecraft has recorded data about the planet’s ring system. It even sent a probe that landed on Titan, a moon that orbits within Saturn’s rings.

Hundreds of scientists from Europe and the United States have studied information from the Cassini mission. Although Saturn’s rings look smooth from Earth, they are actually made up of many pieces of ice and rock. The Cassini mission has shown scientists that this icy combination is similar to what is found on the outer layer of Saturn’s moons.

Could Saturn’s rings be a graveyard for the planet’s earliest moons?

MOON MYSTERY

Saturn is the second-largest planet in our solar system. Some of its moons are huge—Titan, the largest, is even bigger than the planet Mercury.

Saturn has a total of 62 moons. But scientists think it once had many more. Information from the Cassini mission has led them to wonder whether Saturn’s earlier moons fell into the planet’s gravity, breaking into the countless particles of ice and rock that orbit the planet and, from Earth, look like smooth rings.

Because Saturn is so far from the sun, the mantle (inner layer) of the planet’s moons is made from frozen rock. Scientists think that early in Saturn’s history, ice and rock found in its massive moons separated when Saturn’s gravitational pull brought the moons too close. The ice shattered and began to orbit the planet while most of the rock smashed into Saturn’s crust (outermost layer).

If this theory is correct, Saturn’s ring system would be more than 4.5 billion years old. Scientists still wonder how these icy rings could have remained in Saturn’s orbit for so long.

Until now, there have been two major theories behind Saturn’s ring system. One theory holds that comets either were caught by the planet’s gravity, or they struck Veritas, one of Saturn’s former moons. The other theory suggests the rings were made from matter left over when the planet itself was forming.